Certain chemical compounds have long been known in the art to possess the desired quality of imparting softness to textile fabrics. The quality of softness or being soft is well defined in the art and, as used herein, means that quality of a treated fabric whereby its handle or texture is smooth, pliable and fluffy and not rough or scratchy to the touch. Known generally as "softening agents," "fabric softeners" or "softeners," these compounds have long been used by housewives in the laundry and by the textile industry to soften a finished fabric.
Softening agents are usually employed in liquid formulations, and powder, tablet and granular formulations are known. Use of these compositions results in many inconveniences. For example, housewives very often forget to add the softening agent during the rinse cycle of the washing process, thereby necessitating repeated rinse cycles until the softener is timely remembered and added. Additionally, these softening compositions are not generally premeasured; the result is that the housewife often uses an amount insufficient to adequately soften the fabrics or she wastes the softening composition by using excessive amounts or by spillage.
The prior art suggests incorporating fabric softeners into fabric-like substrates, e.g., felted or woven materials such as paper toweling and swatches of cloth or absorbent sponges. In U.S. Pat. No. 3,442,692 a process is described whereby a sheet composed of the above materials and carrying the fabric softener is placed in a laundry drier together with washed, but still wet, fabrics such as sheets, garments, pillow cases, etc.
Impregnated substrates for use in laundering applications are also described in U.S. Pat. No. 3,686,025. In the last mentioned patent the absorbency of the substrate is closely controlled so that release of the impregnated fabric softener occurs slowly and uniformly coats the fabric. Numerous fabric softeners are disclosed along with materials such as sponges, paper and non-wovens as substrates. The preferred substrates are cellulosic materials.